Crushed or processed aggregate of the type used in highways and the like is made up of particles of various sizes ranging from fine aggregate in the 0 to 1/4 inch range to coarse aggregate of 4 inch maximum size. Since the finished highway must have certain characteristics of strength and appearance, it is necessary that the aggregate used be evenly graded in various sizes from dust to 1 inch maximum size, for example. Accordingly, in any stockpile of material that is to be used for such work, care must be taken so that the particles do not separate out according to size and the proper mix of particles is maintained during the stockpiling operation.
The most practical method of stockpiling aggregate involves the use of an upwardly inclined belt conveyor which raises the mix and drops it to form a pile. Unfortunately, when the aggregate is discharged over the upper end of the belt, the larger particles tend to follow a different arc than the smaller particles and, as a result, a stockpile is formed which has larger particles accumulated at one side and smaller particles at the other. Loads of aggregate removed from such a stockpile would not be acceptable for use on many projects.
To assure a proper unsegregated mix, some specifications require that stockpiles be formed by hauling truckloads to a particular site, dumping the loads in side-by-side formation, and then drive a dozer or scraper blade across the top of the several piles to push the peaks of the piles into the valleys and thus form a layer. Additional truckloads are then dumped on the first layer to form several adjacent piles, and the peaks are again pushed over to form a second layer. Additional layers are formed until a stockpile of desired height is obtained. Such a procedure is much more time-consuming and expensive than is a procedure using a belt conveyor.
Several arrangements have been proposed for intercepting material as it is discharged over the upper end of an inclined belt conveyor. Most of these devices are concerned only with redirecting the material so that it is deposited at predetermined locations. Such deflector members are disclosed in the patents to Marston, U.S. Pat. Nos. 962,232, Pratt, 1,381,009, Sterler, 2,563,432, Karlsson et al., 2,577,331 and Aasland, 2,670,839. None of these devices are effective to intercept portions of the material discharged by a belt conveyor, confine each portion against both forward and lateral movement, and then redirect each portion downwardly onto a common stockpile.
In accordance with the present invention apparatus is provided which is arranged to be installed at the discharge end of a belt conveyor to prevent separation of particles of different sizes as a stream of aggregate is discharged over the end.
An object of the present invention is to provide a unique method of preventing the separation of particles of different sizes as a mixture of particles of different sizes is discharged from a belt conveyor and a novel apparatus for carrying out the method.
Other and further features and advantages of the present invention will be apparent from the following description of a preferred embodiment.